This invention relates to a crane, in particular to a mobile crane, comprising an undercarriage and a turntable rotatable with respect to the undercarriage, which can be ballasted with a counterweight and includes a mounting point for the attachment of a winch, in particular of an auxiliary hoisting gear.
Mobile cranes regularly are at least partly demounted for road transport, in order to separately move individual components to the construction site. This is necessary to comply with the prescribed axle loads. Furthermore, it can be provided to attach certain crane components, such as e.g. a hoisting gear, to the crane only as needed. Up to now, such auxiliary hoisting gear has been mounted by the crane itself, i.e. the auxiliary hoisting gear is picked up by the hoisting cable of the crane and lifted to the desired mounting position of the turntable.
In the known mounting methods the auxiliary hoisting gear therefor was first deposited on the counterweight and the crane turntable subsequently was rotated into the desired position, in order to align its mounting points with the auxiliary hoisting gear. In the next step, the auxiliary hoisting gear was lifted to the required mounting height on the crane turntable by means of the ballasting cylinders of the counterweight. This method, however, was found to be unsuitable for novel crane constructions with variable ballast radius, as a larger dimensioned steel construction of the crane turntable is employed. During the rotary movement of the crane turntable collisions with the auxiliary hoisting gear deposited on the counterweight can occur here.
Another disadvantage of this method consists in that the very strong ballasting cylinders have lifted the entire ballast with the auxiliary hoisting gear deposited thereon and have urged the same against a stop. When pressing up further, the auxiliary hoisting gear then has swiveled into the bolting position. Due to inattention (pressing up the ballasting cylinders too much or forgotten timber under the winch of the auxiliary hoisting gear) the auxiliary hoisting gear might disproportionately be pressed against the steel construction of the turntable. For this reason, all involved components of the steel construction as a precaution have been designed for this overload situation caused by operating errors, i.e. the components must be dimensioned very strong and very heavy.